Just played a game of the original Arkham Horror boardgame from 1987. The game started off by giving us 3 gates to deal with. Finished with the doom track one away from "The end of Arkham". Only one Investigator died and needed to be replaced. Introduced 2 new people to this game (both had played more recent versions).
I own the original (this one) and Eldritch Horror. I've also played Arkham Horror v2 and v3. The original holds up remarkably well. It still has the same foreboding feeling but doesn't take an hour to setup. It's more streamlined. Almost as if the later versions bolted stuff on that wasn't needed.
As for the actual question, Eldritch is good, but takes forever to get ready. AH3 is better than AH2, and gives a good immersive experience. I'd say I like them equally.